Upgrade News

September 26, 2006--Upgrade Update: Machine Advisory Committee Formed

An important next step in APS Upgrade planning will be a technical evaluation by an expert committee of the
various accelerator options we are considering. The evaluation will provide guidance to APS and its users
on how to obtain revolutionary performance with minimal disruption to existing users. This review is scheduled
for November 15-16, 2006.

The Machine Advisory Committee is a group of 10 internationally distinguished
accelerator physicists who have very kindly agreed to participate. The list of members and the charge to the
committee are published on the upgrade web site, which will also be updated regularly with details of the machine planning.

Encouraged by our sponsor, the Department of Energy's Office of Basic Energy Sciences, the APS accelerator scientists
and engineers have been considering options for upgrades to the APS. In addition to proposals for storage ring upgrades -
from lower emittance lattices to added ID ports - the concept of upgrading the APS to an energy recovery LINAC (ERL) has
been actively considered. The ERL option generates particular excitement because it not only promises revolutionary performance
improvements but also retains compatibility with the existing beamlines and offers an upgrade path without extended disruption
to user operations.

To help determine the upgrade options that best merit further consideration, we assembled a machine advisory committee (MAC)
of top international experts for a meeting held on November 15 and 16. We presented the feasible options in some detail to the MAC;
their charge for evaluating the options is outlined on the MAC web page.

The committee has submitted its final report, which strongly encourages the ERL approach: "The proposed Outfield ERL is
considered to be an extremely exciting light source which builds on the investment in beam lines and infrastructure already
at the APS. It would provide a factor of about 150 increase in brightness compared to the existing APS in addition to
increasing the coherent fraction of the x-ray beam and significantly reducing the bunch length."

The summary also notes that the other options are viable, but none provides the revolutionary performance improvement
provided by this "Outfield ERL" option.

The committee has recommended that a rigorous research program be initiated to address the technical challenges confronting
ERLs; however, they noted that they are optimistic that these challenges can be met.

All the presentations from the MAC can be found on the APS Upgrade
web page. A white paper on the ERL upgrade will be submitted to DOE in February. As we move forward, we will be discussing
R&D needs for an ERL with the user community, and a major focus of the next APSUO meeting will be development of the scientific
case for an ERL through a number of workshops. For more information about this committee and plans for machine upgrades, please
contact Rod Gerig (rod@aps.anl.gov).